Method of producing printing forms for intaglio printing



Oct. 5, 1965 J. GGRlG 3,210,188

METHOD OF PRODUCING PRINTING FORMS FOR INTAGLIO PRINTING Filed Feb. 6,1962 7 Sheets-Sheet 1 Fig.7

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/NVEN r04 Fig, 4

JOSEF e'c'ame ATTORN EYS Get. 5, 1965 J. GCRIG 3,210,188

METHOD OF PRODUCING PRINTING FORMS FOR INTAGLIO PRINTING Filed Feb. 6,1962 7 Sheets-Sheet 2 INVENro/ JOSEF G6RIG ATTORNEYS Oct. 5, 1965 J.GORIG 3,210,188

METHOD OF PRODUCING PRINTING FORMS FOR INTAGLIO PRINTING Filed Feb. 6,1962 7 Sheets-Sheet 3 III INVENrOP JOSEF eRle ATTORNEYS Oct. 5, 1965 J.GORIG 3,21

METHOD OF PRODUCING PRINTING FORMS FOR INTAGLIO PRINTING Filed Feb. 6,1962 7 Sheets-Sheet 4 Fly 10 Fig 7 INVENTOQ JOSEF ems ATTORNEYS J. GGRIGOct. 5, 1965 METHOD OF PRODUCING PRINTING FORMS FOR INTAGLIO PRINTING '7Sheets-Sheet 5 Filed Feb. 6, 1962 JOSEF G6RIG ATTORNEYS Oct. 5, 1965 J.GORIG 3,210,188

METHOD OF PRODUCING PRINTING FORMS FOR INTAGLIO PRINTING '7 Sheets-Sheet6 Fig, 78

Filed Feb. 6, 1962 mmvro/e JOSEF edRle wwwqw ATTORNEYS Oct. 5, 1965 J.GORIG 3,21

METHOD OF PRODUCING PRINTING FORMS FOR INTAGLIO PRINTING Filed Feb. 6,1962 7 Sheets-Sheet '7 lNVE/VTUP JOSEF sms Mara ATTORNEYS United StatesPatent 3,210,188 METHOD OF PRODUCING PRINTING FORMS FOR INTAGLIOPRINTING Josef Giirig, Schillerstrasse 26, Ditzingen,

near Stuttgart, Germany Filed Feb. 6, 1962, Ser. No. 171,459

Claims priority, application Germany, Feb. 8, 1961, G 31,550 14 Claims.(Cl. 9638) The present invention relates to a process of producingprinting forms for intaglio printing and more particularly to furtherimprovements in the process as described and claimed in my copendingapplication, Serial No. 72,410, filed on November 29, 1960, and entitledIntaglio Printing Screen for superimposing With Autotypy ScreenPositives in the Production of Etchings for Autotypical IntaglioPrinting.

In printing forms for intaglio printing, the image to be printed isgenerally etched or engraved into the printing form so as to be recessedtherein. The tone values which are etched into the printing form arepermeated during the etching by the intaglio screen network. Theintaglio screen is required in the printing forms in order to producethe so-called doctor bars or webs which are necessary for guiding thedoctor. In etching according to originals, the image to be printedconsists of cells of an equal size forming ink wells which are etchedinto the copper to different depths in accordance with the tone valuesof the diapositive and are separated from each other by the raiseddoctor Webs.

The production of etchings according to originals, especially formulticolor printing, can be carried out only under considerabledifficulties which are caused first by the fact that it is not possibleto print proofs of the partial colors as simply and correctly as it ispossible, for example, in offset printing, in order to check them forthe accuracy of their tone values, and, second, by the fact that duringthe etching process the tone values of the originals may becomeconsiderably displaced and falsified.

The effect of these two instability factors is that usually more or lessextensive so-called cylinder corrections have to be carried out on theprinting forms for printing the edition which are quite expensive atleast because of the necessary interruption of the operation of themachine.

Screen positives for variable-surface intaglio printing appear very flatand poor in contrast because of the intaglio screen lines which arecopied in, and it is therefore hardly possible to judge the correctnessof their tone value. Because of this lack in contrast, it is also notpossible to prepare offset copies on zinc plates of these screenpositives and to make a proof thereof by the offset process. The offsetproof would be just as flat and poor in contrast as the screen positiveand it would not in the least correspond with the print attained fromthe intaglio etching.

The objects, features, and advantages of the present invention willbecome apparent from the following detailed description which is to beread with reference to the accompanying drawings.

In these drawings, FIGURE 1 shows a full tone, that is, a surface whichis uniformly colored and has a tone value of 100.

FIGURE 2 shows the reproduction of such a full tone in an intaglioprinting form in which the full-tone surface is permeated by the linesof an intaglio screen which has a linear ratio between white and blackof 1:2.5. Seen as a surface, the lineation amounts to 49% of the entiresurface area of the screen.

See

FIGURE 3 shows a screen diapositive forming the reproduction of aso-called neutral or greywedge, that is, of a tone value extending fromlight-grey to black of an autotypy screen. The tone value thereforeranges in this case from 1 in the upper part of this drawing to in thelower part.

FIGURE 4 shows the same tone value ranging from light-grey to black, butchanged by an intaglio screen according to FIGURE 2 to form a screenpositive for the variable-surface method. For producing the screen, anintaglio contact screen is used with a ratio between white and black of1 to 2.5. A comparison of FIGURE 4 With the autotypy screen according toFIGURE 3 shows that the surface area of the printing elements of thescreen positive according to FIGURE 4 amounts to slightly more than 50%,so that the' range of the tone values extends from about 1 to 50.

FIGURE 5 is a similar illustration of the gradually changing tone valuesbut with the use of a finer intaglio contact screen with a linear ratiobetween black and white of 1:3. The range of the tone value of thescreen positive then amounts to slightly more than 1 to 50.

FIGURE 6 shows the reproduction of the same gradually changing tonevalue in an autotypy screen positive according to the so-called Dultgenmethod, in which the range of the tone value only extends to acheckerboard pattern and also amounts only to 1 to 50.

Summarizing the above, it will therefore be found that according to theconventional manner of breaking up the image, the strongest tone valuein screen positives for intaglio printing amounted only to 50% of thefull tone according to FIGURE 1.

If in the process of producing intaglio etchings the image is to bebroken up by means of screens in order to permit an offset proof to bemade from the screen diapositive for judging the tone values, the screendiapositive should have a full tone value range from 1 to 100. Thisrange is necessary since the screen elements are reproduced in theoffset plate only in two dimensions, whereas in the intaglio etching thesame screen elements have three dimensions so that the amount of ink inthe ink wells of each screen element is proportionally greater, and aproof of the tone values Would be much too strong if the screendiapositive, possibly after having been retouched, would be transferredto the intaglio printing cylinder without change with a tone-value rangeof 1 to 100. Because of the additional depth of the screen elements, thetone value would in this case not need to have a range of more than 1 to50. Screen diapositives with such a low range of tone value are,however, inadequate for proofs in the offset process for the reasons aspreviously mentioned. Theoretically, it would seem to be possible totransfer screen diapositives to the intaglio cylinder which have a rangeof tone value of 1 to 100 and may be used for proofs by reducing thethird dimension of the screen elements, that is, by not etching sodeeply. However, the etching must have a certain depth in order toattain a print of a sufficient color strength.

It is an object of the present invention to produce intaglio etchings bymeans of screen diapositives in such a manner that the latter permit theproduction of proofs with correct tone values by the ofiset method,while preventing the range of the tone value of the intaglio printingforms which are made therefrom from being too large. For attaining thisobject, the present invention provides that the screen diapositives areprepared in a manner so as to have a range of tone values which sufficesfor attaining proofs of correct tone values by the offset method andthat, While the screen diapositives are transferred to the intaglioprinting form, a screen is superimposed thereon which has a transparentcomponent amounting to no more than two thirds of the screen surface andpreferably amounting to about 30 to 60% thereof.

Further details of different modifications of the invention as well asadditional advantages thereof will be apparent from the followingdescription which is likewise to be read with reference to the drawings.

According to one embodiment of the invention, line screens are employedfor being superimposed upon the diapositive. Thus, for example, FIGURE 7shows the autotypy'screen diapositive according to FIGURE 3 on which aone-line screen is superimposed which has a ratio between white andblack of 1:1. The image elements which are etched into the printing formare shown in black in the drawing which also shows at the outer edgesthereof the structure of the one-line screen.

For producing the screen diapositive, either the corn ventional autotypyscreens or contact screens with checkerboardlike screen elements may beemployed. Contact screens of the type as illustrated in FIGURE 8 havealso proved very satisfactory. Contrary to autotypy contact screens withsquare screen elements the screen elements are in this case of anelongated or rodlike shape. The screen positives which are made withsuch screen elements have a shape as shown in FIGURE 9. This screenshape when applied for producing intaglio printing forms has theadvantage over the autotypy screen that the rodlike screen elements arebroken up into dots by the superimposed screen according to FIGURE 7.If, for example, each rod-shaped screen element has a length of 1 mm.and if a screen with 120 lines per cm. is superimposed thereon, threescreen dots will be attained per each rod-shaped screen element.

According to another embodiment of the invention, a line screen isemployed for breaking up the image, that is, for reproducing the tonevalue of the original when producing the diapositive, and thediapositives which then contains the tone values in the form of the linescreen is, preferably after being retouched, transferred in aconventional manner upon a light-sensitive material in which it iscrossed by a line screen. Thus, for example, a picture is taken of theoriginal by means of a line screen, the lines of which extend at anangle of 45, and this screen diapositive is then superimposed during thetransfer upon the printing form by a second line screen, the lines ofwhich extend at an angle of 135. This may be done, for example, byretouching the diapositive with the 45 screen lines in an offset processin accordance with the offset proof so that the individual line screendiapositives of the difierent partial colors will be retouched so as. tohave the correct tone values, whereupon the second line screen with thelines extending at an angle of 135 is superimposed, for example, in theso-called carbon tissue, upon the respective line screen diapositiveduring the transfer of the latter to the printing cylinder.

It is a known fact that the tone values of an original can be reproducednot only in the form of dots of different sizes, that is, by means of adot screen, but also in the form of lines which are wider or a narrowerin ac cordance with the tone value of the original. Such originals willhereafter be called line screen reproductions or line screen positives.Generally speaking, line screen reproductions or positives havepreviously not attained any importance in any printing method, probablybecause they did not offer any advantages over the conventional dotscreen reproductions as were generally applied. For carrying outintaglio printing, the line screen reproduction according to theinventon may, however, be utilized to great advantage.

Line screen reproductions may be produced in the following manner:

(1) The tone values of an original may be reproduced by line screens bymeans of a clich engraving machine of a known design. This machine alsopermits the If line screen reproductions are produced by means of clichautomats, it is advisable to cut the engraving into a photographic layerwhich is blackened by development either before or after the engravingis made. After a proof is made of the line screen reproduction, it isthus possible to carry out in the conventional manner any corrections ofthe tone values as may be necessary in the original engravings by meansof Farmers reducer.

For the purposes of the present invention, the use of a line contactscreen appears to be of special advantage for reproducing the correcttone values. Contact screens as such consist of a film with black lineson a transparent base and a tint which gradually diminishes from theselines toward the transparent center. They are called contact screensbecause they are applied directly upon the light-sensitive layer, forexample, between the negative made from the original and thephotographic material. Such contact screens are commonly employed forautotypy screen reproductions, for book printing, and for oifsetprinting, as well as for intaglio printing for carrying out theso-called variable surface method. Line contact screens have so far notbeen known and prior to this invention there was also no need for themfor carrying out book printing, offset printing, and intaglio printingaccording to the known methods. However, for making reproductions forthe purpose of producing intaglio etchings according to the presentinvention, the possibility of employing line contact screens constitutesan important improvement in the art.

A further embodiment of the invention for producing printing forms forintaglio printing consists in taking two line screen photographs of eachpartial color image in such a manner that, when the two photographs aresuperimposed upon each other, the lines thereof cross each other. Onephotograph is taken, for example, so that the screen lines extend at anangle of 45, while the other photograph is taken with the screen linesextending at an angle of While the photograph with the 45 lines isretouched and used for producing the offset proof, the photograph withthe 135 lines may remain unretouched since it is only required forforming the doctor bars or webs which are necessary in the printingform. For producing the printing form, the line screen positives withthe angles of, for example, 45 and 135 are successively copied upon thecarbon tissue. A printing form which is made in this manner is similarto a printing form for which the screen positive has been made by meansof a cross screen for the variable-surface method. The two kinds ofprinting forms differ, however, by the fact that in the variable-surfacemethod the screen points have straight sides, while those in theabove-mentioned example are curved or bent in accordance with the courseof the lines of the two line screen positives which are copied upon eachother.

This embodiment of the invention is illustrated in the drawings. FIGURE10 shows a section of a line screen positive which has been producedaccording to the invention, FIGURE 11 shows the carbon tissue copy ofthis line screen positive, FIGURE 12 shows this carbon tissue copy afterthe second line screen has been copied thereon at an angle of 135,FIGURE 13 shows the carbon tissue copy according to FIGURE 12 afterbeing transferred to the printing cylinder, while FIGURE 14 shows theetched image according to FIGURE 13 on the printing cylinder.

Thus, by means of a line screen which is set at an angle of, forexample, 45 and has a ratio of white to black of 1:3 a line screendiapositive of a partial color image according to FIGURE is first madeof the original to be reproduced. A proof may then be made, for example,by the offset method, of this diapositive as well as of the line screendiapositives of the other partial color images. This proof may be usedas a basis for retouching the diapositives. Thereafter, a copy of eachline screen positive is made in the usual manner on carbon tissue, asshown in FIGURE 11, in which the black lines indicate exposed gelatineand the white lines indicate unexposed gelatine. The line screen is thencopied over this carbon tissue copy so that the image structureaccording to FIGURE 12 is attained. This carbon tissue copy which isprovided with the two line screens is then transferred to the printingcylinder and the unexposed gelatine is washed out so that the copy thenhas the appearance as shown in FIGURE 13, in which the black linesindicate hardened gelatine and the white areas the unexposed parts ofthe surface of the intaglio printing cylinder. After etching andremoving the hardened gelatine, the printing cylinder shows the image inaccordance with FIGURE 14 which illustrates that the size of the colorvalues is determined by the lines which are of an irregular width andextend at an angle of 135, while the webs of an equal width which extendat an angle of 45 serve as doctor guides and limit the intermediate inkwells in their position.

According to another embodiment of the invention as previouslymentioned, aline contact screen according to FIGURE 15 is employed inplace of a normal line screen for breaking up the image or forreproducing the tone values. In this line contact screen, theline-shaped areas between the black lines have a shading which graduallydecreases in strength from these lines toward the center Where only anarrow transparent line remains.

The above-mentioned order of succession of copying the line screendispositive and the line screen upon each other in the carbon tissue isnot compulsory. It is also possible first to copy a line screen of 45into the carbon tissue and then to copy over it the retouched linescreen positive. Also in this case the same structure as shown in FIGURE12 will be attained. It is, however, impossible to copy both linescreens simultaneously with one exposure since the lines of the screenpositive and of the intaglio screen would then cover each other at thepoints of intersection and no blackening or hardening of the chromategelatine would then occur with the result that the doctor webs would notrun through in the printing form.

For the further embodiment of the invention as illustrated in FIGURES 16to 19, two photographs are taken for each printing form by means of aline screen with an angular osition of 45 and a line screen with anangular position of 135. As previously mentioned, only one diapositive,for example, according to FIGURE 16, is then retouched and used formaking proofs. The two positives are then copied upon each other in thecarbon tissue in the manner as illustrated in FIGURE 18. The blackline-s again indicate exposed areas and the white areas unexposedgelatine. This carbon tissue copy according to FIGURE 18 then results inthe etching on the printing cylinder as shown in FIGURE 19.

This last-mentioned embodiment of the invention has the advantage overthe other embodiments that, because of the employment of line screens inplace of cross screens for taking the photographs and for copying-over,only one angular position together with its complement which is 90larger, that is, in the particular examples as described the angles of45 and 135, are required, whereas when employing cross screens forsplitting up the image as well as for superimposing the screens whichform the doctor webs, each two angular positions are required whichdiffer, for example, by 90 from each other so that in superimposing, anangular displacement of at least 15 must be carried out. This necessityis avoided in the present embodiment of the invention so that the dangerof a moir formation is still further reduced or prevented entirely.

It should further be pointed out that the ratio between the transparentpart to the opaque part of the line screens as applied may be variedconsiderably in accordance with the requirement-s in each particularcase. Thus, for example, the ratio between white and black of the linescreen in which the copy is traversed by the line screen positive mayalso amount to 1:1 or 1:4, rather than 1:3 as previously mentioned. Itis also not necessary that the line screen positive and the line screencrossing the same have the same number of lines. For example, the linescreen positive may have 60 lines per cm., while the intaglio linescreen has lines per cm., or vice versa. Finally, the lines of the linescreen also do not have to be straight but they may be wavy or in somecases even be broken but not interrupted entirely but so as to extendthrough the entire length thereof.

If after a line screen, reproduction has been retouched and a proof beenmade thereof, so-called multiple dias are required thereof, the linescreen which crosses the line screen positive may already be copied intothe negative during the recopying.

In the manner as illustrated in the drawings, it is possible forproducing the intaglio printing form according to the invention toemploy screen positives which are attained by means of autotypy screens,one-line screens according to FIGURE 15, or rod-shaped screen elementsaccording to FIGURE 8. Naturally, screens of other design-s may also beused.

The above description relates to the manner of carrying out the basicconcept of the invention and to the different embodiments thereof Whileapplying the usual processes of reproduction, that is, the production ofthe partial color images by means of a photographic camera, theproduction by photographic means of the screen di-apositive of thenegative as attained by the photograph, the transfer of the screendiapositive, possibly after retouching for the correction of the tonevalues, to the light-sensitive mate-rial of the so-called carbon tissueand the superimposition thereon of the sec-0nd screen which reduces thetransparent component in this carbon tissue or in the transfer to theprinting cylinder, and the production of the screen image in theprinting form, that is, for example, on the copper intaglio printingcylinder by chemical etching.

Printing forms for intaglio printing may, however, also be produced byclich engraving machines by electromagnetic means by scanning anoriginal photoelectrically. Such methods are described, for example, inthe published German patent applications of Hell, DAS 1,004,923 and DAS1,004,877.

It has now been found that the known electromagnetic engraving processmay also be advantageously applied for carrying out the method accordingto the different embodiments of the present invention for producingprinting forms for intaglio printing by the employment of screendi-apositives and a second screen superimposed thereon. For thispurpose, a screen positive is first prepared either by photolithographicmeans or electrornagnetically by a clich engraving machine. After aproof is made and possibly also a correction of the tone value iscarried out, this screen positive is transferred to the printing form bythe electromagnetic or electronic means of one of the known apparatus,whereby the range of the tone values is reduced to the desired extent.This is preferably done by photoelectrically scanning only a certainpart of the existing screen elements in the screen positive and byengraving the same electromagnetically into the printing form. Duringthe transfer to the printing form, the screen elements are thensuperimposed according to the invention by a screen which has atransparent component amounting to no more than about twothirds of thearea of the screen surface and preferably to about 30 to 60% thereof. Inthe end result, the printing form which are thus attained thereforecorrespond to those previously proposed by the inventor and especiallythose according to the present invention.

The reduction of the range of the tone value in the electromagnetictransfer of the screen diapositive to the printing form may be carriedout with considerable advantages and in a relatively simple manner ifthe screen diapositive is provided with a line screen design. This phaseof the invention will now be described with reference to the drawings.

For transferring the screen positive according to FIG- URE to theprinting form, the same is inserted, for example, into anelectromechanic intaglio engraving machine as described in the mentionedGerman published patent application DAS 1,004,923, but at such anangular position that the direction of operation of the photoelectricscanning head extends to the screen lines of the positive at an angle,preferably of 90, as indicated in FIGURE 21 by the hatched stripes.Whereas the manner of operation as described in the mentioned Germanapplication DAS 1,004,923 requires that a screen frequency issuperimposed upon the control voltages of the engraving system, this isnot required in the method according to the invention since the scanninghead which has a width equal to that of one of the hatched stripes asshown in FIGURE 21 meets the transparent stripes, which are indicated inwhite in FIGURES 20 and 21, either before or after crossing a screenline so that the engraving tool will then be automatically lifted. Onthe other hand, when the engraving of each row of screen dots iscompleted, the transverse feed of the scanning and engraving systemshould be shifted by a multiple of the width of the scanning head andengraving tool so that the system will not again be switched on until acertain distance has been left free which corresponds to the whitestripe in FIGURE 21 which extends at an angle of 135, whereupon thewidth of the next hatched stripe is scanned. This transverse feed of thescanning and engraving system should be adjusted so that the unscannedwhite stripes extending in FIGURE 21 at an angle of 135 practicallyproduce a reduction of the range of the tone value to no more than abouttwo thirds, preferably to 60% of the full value. The black areasindicate the intersecting of the scanning head with the opaque lines ofthe screen positive, and these black areas form those parts of theoriginal which are engraved into the printing form, as indicated inFIGURE 22.

In this embodiment of the invention the tone values of the screenpositive according to FIGURE 20 are made lighter in the printing formaccording to FIGURE 22 by about 50% and this printing form thereforeequals one as produced photochemically according to the invention. Thedegree of lightening up the tone values may, of course, also be variedin this case by varying the distance between the individual lines to bescanned. The fineness of the screen lines extending in the transversedirection as produced electromechanically or electronically as comparedwith the lines of the screen negative is determined by the width of theengraving tool.

Although my invention has been illustrated and described with referenceto the preferred embodiments thereof, I wish to have it understood thatit is in no way limited to the details of such embodiments, but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed my invention, what I claim is:

1. In the method of producing an intaglio printing surface from anoriginal having a range of tone values, the steps comprising (a) makinga screened diapositive from said original reproduction, said diapositivehaving the full range of tone values present in the originalsufiicierrffor making a proof print by the offset process,

(b) printing by offset a proof of said diapositive,

(c) retouching the diapositive to correct the tone value thereof asindicated by the offset proof,

(d) then transferring the configuration of the screened diapositive ontoa printing surface to be relieved in the image areas for intaglioprint-ing,

(e) forming on said printing surface a doctor bar forming second screenconfiguration, in which the doctor bar forming screen configuration hasa doctor bar forming area amounting to no more than twothirds of thetotal printing surface area, and

(f) relieving the printing surfaces to form ink receptive Wells thereinaccording to the combined configurations produced in steps (d) and (e).

2. In the method of producing a set of printing surfaces for multi-colorintaglio printing from a set of color separations, the steps comprising(a) making a separate screened diapositive from each separation, eachdiapositive having the full range of tone values present in the originalfor making an offset proof from that diapositive,

(b) retouching said diapositives to correct the tone value thereof,

(c) printing by offset proofs of each of said diapositives,

(d) again retouching said diapositives as indicated by the tone valueexhibited in ofifset proofs,

(e) transferring each said diapositive to a separate printing surface tobe prepared for intaglio printing,

(f) superimposing on each said printing surface an intaglio screenconfiguration in which the doctor bar forming transparent componentoccupies no more than two-thirds of the area of the surface, and

(g) relieving each said printing surface to form ink receptive wel-lstherein according to the combined configurations produced in steps (e)and (f).

3. A method as defined in claim 1, in which said screened diapositiveand said second doctor bar forming screen are combined by copying themin separate stages into a light-sensitive carbon tissue, and in which,after these two exposures are made, said carbon tissue is transferred tothe printing surface.

4. A method as defined in claim 1, in which two photographs are taken ofthe original by means of line screens each having screen lines extendingat an angle to those of the other screen, retouching one of saidphotographs to form a screen diapositive, and then copying the retouchedscreened diapositive and the other unretouched photograph over eachother into a light-sensitive material such as carbon tissue.

5. A method as defined in claim 1, in which the print ing surface isrelieved by means of a conventional etching process from thesuperimposed screened diapositive and doctor bar forming screenconfiguration transferred to the printing surface.

6. The method of producing an intaglio printing surface as defined inclaim 1, in which step (e) comprises forming on the printing surface adoctor bar forming screen configuration in which the doctor bar formingarea amounts to between 30 and 60% of the surface area of the doctor barforming screen used to produce this configuration.

7. The method of producing an intaglio printing surface as defined inclaim 1, wherein step (e) embodies the formation of a doctor bar formingline screen configuration having a ratio of doctor bar forming area toprinting area which is between the range of lz l and 1:2.

8. A method of producing an intaglio printing surface as defined inclaim 1, in which step (a) includes the making of a screen diapositivefrom the original through a contact vignette screen having a screenformation of rod-shaped opaque screen elements arranged in acheckerboard pattern.

9. A method of producing an intaglio printing surface as defined inclaim 1, wherein step (21) includes the making of two diapositives fromthe original through line screens, with the lines in the screen used tomake one diapositive being arranged at an angle with respect to thelines of the screen used to make the other diapositive, and wherein saidone diapositive is used for steps (-b) and (c), and wherein step \(d)includes the transferring of the configuration of both said onediapositive and said other diapositive, in superimposed relation, ontothe printing surface to be relieved.

10. The method of producing a set of printing surfaces for multicolorintaglio printing as defined in claim 2, in which step (a) is performedby using a line screen having opaque lines formed as areas of graduallyincreasing transparency, and in which such screen is used as a contactscreen in the making of each separate screened diapositive.

11. The method of producing a set of printing surfaces for multicolor inprinting as defined in claim 2, in which step (a) includes the making ofscreened diapositives in which the opaque component of the screen islarger than the transparent component thereof.

12. The method of producing an intaglio printing surface as set forth inclaim 1, in which step (d) comprises transferring the configuration ofthe retouched screened diapositive resulting from steps (a), (b) and (c)onto said printing surface by means of an electrical engraving device inwhich the range of the tone values is modified to reduce the tone valuesby a predetermined amount.

13. A method as defined in claim 12 in which only a certain portion ofthe screen elements of the screened retouched diapositive isphotoelectrically screened and electromagnetically engraved into saidprinting form.

14. A method as defined in claim 12 in which the screened diapositive isformed by exposure through a line screen to cause the tone valuesthereof to appear in the form of continuous but separated lines, andwherein the transfer-ring of the configuration of the screeneddiapositive onto the printing surface is performed by scanning suchscreened diapositive at an angle of approximately 90 with respect to thelines of the screened diapositive.

References Cited by the Examiner UNITED STATES PATENTS 591,653 10/97Levy 96-116 1,307,824 6/19 Larsen 96-116 1,375,659 4/21 Illig 96-1161,460,744 7/23 'Boysen 96-116 1,919,481 7/32 Rowell 96-116 2,010,0428/35 Stirling 96-38 2,039,195 4/ 36 Stirling 96-38 X 2,126,479 8/38Landrock 96-116 2,159,588 5/39 Gorig 96-38 X 2,183,204 12/39 Reynolds96-116 2,811,444 10/57 Wattier 96-37 3,085,878 4/63 Archer 96-118FOREIGN PATENTS 16,447 12/03 Great Britain. 421,5 29 1/ 35 GreatBritain. 770,864 3/57 Great Britain.

OTHER REFERENCES The Lithographers Manual, vol. 1, January 1958,Waltiven Publishing Co., New York, N.Y., pp. 11:1-11110.

NORMAN G. TORCHIN, Primary Examiner.

1. IN THE METHOD OF PRODUCING AN INTAGLIO PRINTING SURFACE FROM ANORIGINAL HAVING A RANG OF TONE VALUES, THE STEPS COMPRISING (A) MAKING ASCREENED DIAPOSITIVE FROM SAID ORIGINAL REPRODUCTION, SAID DIAPOSITIVEHAVING THE FULL RANGE OF TONE VALUES PRESENT IN THE ORIGINAL SUFICIENTFOR MAKING A PROOF PRINT BY THE OFFSET PROCESS, (B) PRINTING BY OFFSET APROOF OF SAID DIAPOSITIVE, (C) RETOUCHING THE DIAPOSITIVE TO CORRECT THETONE VALUE THEREOF AS INDICATED BY THE OFFSTET PROOF, (D) THENTRANSFERRING THE CONFIGURATION OF THE SCREENED DIAPOSITIVE ONTO APRINTING SURFACE TO BE RELIEVED IN THE IMAGE AREA FOR INTAGLIO PRINTING,(E) FORMING ON SAID PRINTING SURFACE A DOCTOR BAR FORMING SECOND SCREENCONFIGURATION HAS A DOCTOR BAR FORMING AREA AMOUNTING TO NO MORE THANTWOTHIRDS OF THE TOTAL PRINTING SURFACE AREA, AND (F) RELIEVING THEPRINTING SURFACES TO FORM INK RECEPTIVE WELLS THEREIN ACCORDING TO THECOMBINED CONFIGURATIONS PRODUCED IN STEPS (D) AND (E).